Precision centering device



April 5,1949. L, R CLARK 2,466,380

PRECISION CENTERING DEVICE Filed Nov. 4', 1944 INVENTOR rroR/VEK Patented Apr. 5, 1949 UNITED STATES PATENT OFFICE Y 2,466,380 y PRECISION CEN'rERING DEVICE Leland E., Clark, AE1 Monte, Calif. Application November 4, 1944, Serial No. 561,886

3 Claims.

This invention relates to machiniststools and more particularly to precision gauges of the type commonly employed in positioning a piece of work on a machine with relation to the cutting tool of that'machine so that subsequent operations performed by they tool Will'be located in exactly the desired portion of the work.

An objecthof my inventionV is to provide` a machinistsgauge of thecharacter indicated, the function of which isA to'a'iiord convenience in locating Work, or setting up, as itis called in the trade, on machines wherein the cutting tool is carried by a rotating spindle, such as a vdrill press or vjig-borer, whereinothestep of ,setting up entails arranging the work-with a certain predeterminedpoint thereon in exact alignment with the machines spindle.

A more detailed object of thewpresent invention is to provide a centering gauge of the character indicated, which is adapted to be ,mounted directly upon the machines working spindle, as by means of the chuck with which such machines customarily are equipped, thus facilitating aligning the gauge with thehspindlesraxis quickly and with extreme accuracy.

Another object is to provide an assortment of work-engaging feelers and means for mounting any selected one of'them in operating position upon the gauge whereby the gauge is adapted for aligning a predetermined part of a piece of work with a machine operating tool, regardless of whether the part of the wor-k so tobe aligned is in theform of a center punch mark, crossed scribe marks, or a` hole or a projecting pin'of circular cross section. V

Yet another object ofY my inventionis to arrange the working parts of the gauge in such a manner that therindicating dial and the immediatelyhassociated portions of the device, while being fully sensitive to movements of the pick up iinger, or work-engaging feeler, even though such movements vmay be of nogreater ymagnitude than the ysmallest fraction of an inch of which cognizance is taken in even the most skilled and precise machine work, are fully protected from damage which otherwise might result from severe shockimparted to the feeler; such as that which the feeler might experience when the gaugewis dropped or inadvertently struck with another Atool or heavy piece of material. y

It is a 4further object of the present invention to provide a centering gauge of the general character described which is extremely sensitive and precise in its operation, is relatively simple and inexpensive in construction, and is possessed of 2 ample strength and ruggedness to insure practicable durability.

The invention possesses other objects and valuable features, some of which, With those enumerated, will be set forth in the following description of the preferred embodiment of my invention illustrated in the drawing accompanying and forming a part of the speciflcation.` It is to be understood that I do not limit myself to the showing 'made bysaid drawing and description but that I may 'adopt variations of the preferred form within the 'scope of my invention as dened by theclaims.

Referring to the drawings: t

Figure 1 isa View in side elevation of a centering gauge embodying the principles of the present invention. t y l Figure 2 vis an enlarged View in longitudinal medial section taken upon the line' 2-.2 of Figure'l, with the direction of view as indicated. In this View the balance weight for holding the body of the tool stationary is omitted.

Figure 3 is a longitudinal medial sectional view taken upon the line 3-3 of Figure 2, with the direction of view as indicated, and showing the pointer, or pick up nger arranged within a hole, the axis of which constitutes the significant portionof the piece of work to be aligned with the spindle of the machine in which the centering gauge isfmounted'.,

Figure 4 is a detail View showing a slightly modied form of pick up finger or pointer intended to be used in conjunction with a center punch mark or a pair of crossed scribe marks.

Figure 5 isa'slightly enlarged view showing a still`furthermodiedform` of pick up finger intended for use in'conjunction with a projecting pin of circular cross section. f

In the modication thereof chosen for illus-- tration and description herein, the centering gaugehofmy invention comprises a shaft Il disposed centrally of and extending through a body I2 which is journalled uponthe shaft II as by axially aligned bushings I3 and I4. Both the inner and outer ends I 6 and I'I, respectively, of

theA shaft II extend beyond the associated ends of the body I2, the former thus presenting a shank adapted to be received within the chuck of a machine suchas a drill press or jig-borer andthereby mount the entire centering gauge directly upon and accurately in co-axial alignment with the rotating spindle of that machine. The extended outer end Il of the shaft Il has a preferably circular head I8 rigidly secured thereto in any convenient manner, `as by being press tted thereon. An annular flange 22 extends outwards from the head I8; and an arm or lever 23 is pivoted within a slot 24 in the outer edge of the flange 22 as by a pintle pin 26 extending across the slot 24. The lever 23 extends radially inwards from the ange 22 and supports a mounting head .2l on its inner end substantially in alignment with the axis of the shaft Il. This mounting head conveniently takes the form of a pair of spacedflanges 28 interconnected by. a screw 29 having `a nut 3l threaded thereon so that a block 32 disposed between the flanges 28` may be pivotally mounted upon the screw 29-- and may be yieldably retained by frictionin'any,Y

selected position of rotary adjustment about the axis of the screw 29, such frlctional retention.

being attained by proper adjustment of. the nut..

In the outer face of the block 32 an interiorly" threaded socket 33 is formed for the reception.:

of the threaded end 34 of a "pick up finger or feeler 36; the outer end31 -of whichisadapted to. engage the work 38, for the positioning of which withfrespect, to the axis of the spindle upon which the gauge ismounted, the centering gauge of my invention is employed.

Since the feeler 35-is releasably secured to the block 312 by means of the-threaded engagement described; various types of feelersmay besupplied with the centering. gauge, and the particu-- lar, one best suited. for any particular typeyof work may be selected; In Figuresl, 2,-.and 3 thetype illustrated is provided with aballf39,A on its outer end, this being the type of feelerintended for use when setting; up a piece of workin. such amannerthat the axisof a hole or socket dglfof circular cross section is to be.` aligned withthe axis of rotation of the machines spindle.

.Figure 5 illustrates amodied form of pick up1f1nger or feeler` adaptedy tobe used-in conjunction witha projecting pinor other projection of circular cross section; the axis of which isto be brought accurately into alignment wih the axis' ofthe machines spindle. This pickup nger 4.2 comprises a short .rod preferably more or less aduncate in formr so that its outer-end 43is deflected inwardsy to facilitate'engagement of the end ofthe linger 42 ,with the circular surface of the projection 44; Theoppositeend of the finger 4 2 is'provi'ded with a'threaded. male element 46 releasably engageable within the threadedfsockct 33 of the block 32 so as to mount the pick up?y fingerj42 in operativevpositionlupon the lever 23.

`Il igurel` shows astill further modified form of pickup fingers-or. feeler 51I-comprising a small cylindrical housing. 52 having-a threaded male element 53 Yatone end for. mounting` the. pointer 5l upon the block 32 Within the hollow interior of the housing .52 a plunger 54-is `reciprocably mounted with the outer end 5Fl-ofthe plunger54 projecting beyond the outer endof the=housing 52.and provided with arelatively sharp point 5.1 adapted to seat. within a center punch mark 58 in a piece of work59. Retention of the point 51 within the center punch mark 58 is facilitatedby means of a coil .spring 6| -under compression withinthe housing 52 and continuallyurging the plunger 54 outwards, i, e.,.to.the right. as viewed .upon Figure 4. I have found in actual .practice that by using a spring-urged plunger 54 as yde..- scribedand one whosepointl is relatively sharp, a .veryshallow centerpunch mark 58 oreven as slight a depression as thatwhich .iseformed by apair ofintersecting scribev niark'sis sufficient to lretainthepoint of the .pick.up,. arm 5I..

Aii)

An axial bore 66 extends inwards from the outer end l1 of the shaft Il far enough to enter the hollow interior 61 of the body I2 and a push rod 68 is slidably mounted within the bore 63. The outer end of the push rod 68 abuts against the inner face of the lever 23, and the inner end of the push rod abuts against a transversally extending rod 69, the ends of which project through radial slots 'H in the shaft il, and are rigidly connected to a sleeve 12 which is slidably mounted upon the exterior of the shaft H. A coil spring 'I3 is under compression between the inner end of the sleeve 12 and a washer i4 which engages-,thef-inner face of a head '16 which closes the inner end of the body i2. The head 'l5 is removablysecured in position upon the body I2 aszbyaplurality of counter-sunk machine screws Tl, thus permitting easy access to the interior 61 ofzthe.. body I2 to facilitate assembly of those portions of the device which are arranged thereinsi. de.v The coil spring'lS continually urges the sleeve-.152- to itsY outer extreme of. movement as determined by engagement of the transverse rod 69.1 With' the distal ends. ofthe slots 1 I.

. An opening 8fl'in the wall. of the body l2 forms asocket forthereceptionof va dial indicator 82; and whereas` anysuitable type ofV dial indicator maybe employed, that which I have found most advantageous for usein connection with the centeringgauge of the, present invention is the one whichcan be purchased.- onthe open market un- ,denthe tra.gie-markl Last VllordffA inasmuch as thedetails of. vconstructiony ofthe dial indicator 82 form no portion of; the. present invention, it Will= jsuie. for the .purpose ofl the. present disclosure `to explain thatit comprises a substantially cylindrical body 83A having4 an enlarged head 84.at one end to accommodate a dial 86 andan-indexl.movable withy respect thereto in K-response'to movementof a pivotally mounted finger 88 at the opposite end; of the body 83 to which the index 81 is connectedby suitable actuating mechanism .(not shown). The actuating finger` Sil-ofI the dialfindicator 82engages the outer end of the sleeve 12, against which itis pressed by a spring (not shown). which is included in theldialindicator 8:2, Inasmuchasthe push rod $8;` isn not positivelyconnected tot the lever 23 orto the transverse rods!! butl merely abuts thercagainst, it can cause movement of the sleeve 12 only-.tothe left as viewed upon Figure 2, and the, spring 1.3 is the only. element which can cause movement .of the sleeve l2 in that direction wherein. it moves the finger 88 of the dial indicator 82. This is an important featureof my invention inasmuch Ias it prevents damaging of the.diallindicator82 eventhough some violent shock may be imparted-tothe pushfrod 88 as by droppingthe entire instrument. or by .striking the -pick. up feeler'orthe lever-23 with another toolon with a relatively heavy piece of material.

.Adjacent its inner. end the body I2 is provided with preferablya. pair. of interiorly threaded sockets- SLWithin either. ofv which a tubular plug 92.v isremovably receivable. Ahrod 93. extends through. the-plug .92, being retained therein by a ball. 94 on the inner end of the rod 93. VA weight 96. (see Figurerl) is adjustably mounted upon the the shaft I upon which the body l2 `is supported is rotating with respect thereto.

. Y Operation As hereinabove explained, it is intended-that the centering gauge of the present invention'be mounted upon a machine suchas a drill-press or jig-borer with the shaft accurately in axial alignment with the working spindle of that machine. The function of 'the centering gauge is to indicate whether or not a certain predetermined point on a piece of work 38 is accurately in alignment with the axis of the machines spindle so as to enable the machinist operating the machine so to adjust the work uponthe bed ofthe machine as to bring that pointjon the work accurately into alignment with the" spindle, thus setting up the work 38 fori-the purpose of enabling the machine to perform a certain predetermined cutting or forming operation upon the work exactly in the desired location thereon. In accordance with the hereinabove description, if the point on the Work 38 to be brought into alignment with the spindles axis is indicated by a center punch mark, the pick up feeler 5| illustrated in Figure 4 should be selected and mounted upon the block 32 in the manner described. However, if the axis of a projecting pin or other projection of circular cross section constitutes the significant point on the work 38, then the pick up feeler 42 illustrated in Figure 5 should be employed, and when the axis of a cylindrical hole such as that indicated at 4| in Figure 3 is to be brought into alignment with the machines spindle, then the pick up feeler 38 having a ball 39 at its outer end should be employed. As already explained hereinabove, the nut 3| should be tightened upon its screw 29 sufficiently to press the flanges 21 fairly tightly against the block 32 and thereby yieldably retain the block 32 and the pick up feeler 36 carried thereby in selected position with respect to the lever 23. As a consequence of this arrangement, any lateral movement of the pick up feeler 36 will be accompanied by rotary motion of the lever 23 about the axis of its pintle pin 26 until, of course, the lever 23 reaches the limit of its movement after which continued movement of the pick up feeler 3B in the same direction will be about the axis of its pivotal connection to the lever 23.

Assuming that the work being set up requires alignment of the axis of a hole such as that indicated at 4| with the axis of the machines spindle, the work 38 should be placed tentatively in position upon the bed of the machine with the hole 4| as nearly axially aligned with the machines spindle as conveniently can be accomplished by eye and the bed then adjusted to move the work 38 toward the centering gauge until the ball 39 at the end `of the pick up feeler 36 enters the hole 4|. The spindle of the machine then. should be started in rotation with the outer end of the pick up finger slidably engaging the interior surface of the hole. Any deviation of alignment of the hole 4| with respect to the axis of the machines spindle will cause the feeler 35 to move back and forth, i. e., to move laterally with respect to the axis of the shaft However, since the rotary motion of the lever which accompanies lateral movement of the feeler 36 is about an axis which is oiiset laterally from the axis of the rotation of the shaft II and which lies in a plane to which the axis of the shaft I I is perpendicular, any such lateral movement'of the pickup'feeler 36 likewise l-willloe accompanied by motion of the push 'rod 68." 'That is tosay, whenthe"pick up feeler 36 moves downward as viewed'upon Figure 3, the lever 23 5 will becaused to move inwards, i; e., to the left, pressing the push rod-68 inwards and carrying with it the sleeve 12. This will-permit the finger 88 of the dial indicator 82 to move to theleft as viewed upon Figure 2 in response to the action of its own motivating spring (not shown). When the pick up nger moves upward as viewe'dupon Figure 3, the lever 23 will swing outward, i. e., to the right, permitting the spring 13 to move the sleeve 12 and the push rod 68 outward, i. e., to the right, carrying with it the outer end of the finger 88 of the dial indicator. Thus it may be seen that any lateral movement of the pick up finger 36 willfcause corresponding movement of the finger 88 of the dial indicator, which of course will produce corresponding movement of the index 81 over the face of the dial 86. Since the extent of such movement of the index 81 constitutes a measure of the distance which the axis of the hole 4| is offset from 25 the axis of rotation of the machines spindle, the

machinist is enabled to adjust the work 3s upon the bed of the machine until the oscillation of y the index 81 is reduced to zero at which time he will know that the axis of the hole 4| has been brought with extreme accuracy into alignment with the axis of rotation of the shaft and the spindle of the machine upon which the centering gauge is mounted.

I claim:

1. A centering device of the character described comprising a shaft, a body journalled on said shaft, means associated with said shaft and extending beyond said body for mounting said centering device, means for restraining said body 40 from rotating while said shaft rotates with respect thereto, a feeler pivotally mounted on said shaft for movement about an axis lying in a plane to which the axis of said shaft is perpendicular whereby lateral movement of said pointer with respect to said shaft results from rotation of said shaft while said feeler engages work at a point offset from the axis of said shaft, said feeler comprising a housing having a bore, a plunger reciprocally mounted therein with an end of said plunger projecting therefrom, and a spring under compression between said housing and plunger and urging said plunger outwards, and indicating means operably connected to said feeler and actuated by said lateral movement thereof.

2. A centering device of the character described comprising a shaft, a body journalled `on said shaft, means associated with said shaft and extending beyond said body for mounting said centering device, said body having a pair of sockets on opposite sides thereof, means for restraining said body from rotating while said shaft rotates with respectthereto comprising a rod, means engageable optionally in either of said sockets for securing said rod to said body, and a weight carried by said rod, a feeler mounted on said shaft for pivotal and axial motion with respect thereto, and indicating means carried by said body and operably connected to said feeler to be actuated by axial motion of said feeler and including a dial facing outwards with respect to said body in a direction substantially perpendicular to a diameter of said body passing through both of said sockets.

3. A centering device of the character described exwhdihgl-hyandsaid bpdyfffor. mauniingf Said centering. device;- af-feeler; niytallymhuhtfed 01.1

laterally from@ the axis r'Orf Said; Shaft: and; lying 11.1: a. piane:V @Q whinhfsaidshafts axis is. perpendicular whegcebyylaterai movementhof. said feeler about; said axis fof-lits fp ivotal ,mounting is; accompanied by axial.' movement Uhereof,` a. push rod slidably minimisedl within anv f axial shore in. said 4shan;` and-operablyfconneoted'tojsaid feeler to be reciprocated'in response. t9 axialmoton thereof,

ai Sleeve; difposedvwithh 'Said hollowhQdy, and

mounted for, reciprocate@ motion y on saidshaft, means connecting esaid; sleeve iso-said push rod w hemovediherewith, lSaid .body having. asoket therein; an indicatorgcomprising. af body receivable Withinzsaidfsocket, an actuating finger` pivotf ally mounted Vcm*- said'bodyfinf position:y to extend arev of record in the Nnmber- 'Name' Date VA122645910 Elsasser ;May 7, 1918 13373.319v 1 `Ferrand Mar. 29, 1921 '1,424,310 v Krebsl- AugifI, 1922 '15123,529 Y Schweiterman f Aug'. 6, 1929 

